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    //   class Foo { }
    //   class Baz extends Foo {
    //     static [Symbol.hasInstance]() {
    //       return false
    //     }
    //   }
    //   const b = new Baz()
    //   console.log(b instanceof Foo)
    //   console.log(b instanceof Baz)
    // let initial = ['foo']
    // let array = ['bar']
    // console.log(array[Symbol.isConcatSpreadable])
    // console.log(initial.concat(array))
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